This invention relates to tissue grafting.
An increasing number of surgical techniques are now performed arthroscopically. For example, arthroscopic procedures include reconstructing the anterior cruciate ligament (ACL) as well as the posterior cruciate ligament (PCL) in the knee.
When the ACL has ruptured and is nonrepairable, it is usually replaced in the knee using a substitute graft harvested from the patient or from a donor. For example, the substitute ACL graft may be selected, according to surgeon preference, from a portion of a patellar tendon having a bone block or plug at each end. Alternatively, artificial grafts formed synthetically or with a combination of artificial and natural material, such as a ligament augmentation device (LAD) to which tissue is sutured, may be used as a substitute graft. The term "graft" is used herein to encompass all of these tissue replacement items. Several ACL reconstruction techniques are described in U.S. Pat. No. 5,139,520, incorporated herein by reference.
Referring to FIG. 1, in one technique, an ACL graft 1 is inserted through bone passages 2 and 3 formed in a femur 4 and a tibia 5, respectively. These bone passages are formed by first using a drill tipped guidewire (not shown) to provide a hole extending through the bone followed by a larger drill which provides a closed-ended socket larger than the guidance hole and having a width at least as large as the width of the ACL graft 1. For example, with respect to femur 4, the drill-tipped guidewire initially forms a hole 8, and bone passage 2 is formed in the femur only after a larger drill is used to ream the original hole 8, so that graft 1 is allowed to pass through the roof of the intercondylar notch 6 (the portion of femur 4 flanked by two femoral condyles 7). Similarly, bone passage 3 in tibia 5 is formed by reaming with a larger drill only after a hole 9 is drilled by the guidewire. Subsequently, ACL graft 1 is secured in bone passages 2 and 3 by sutures 11 and suture anchors 13. The fully formed bone passage 3 passing through tibia 5 and accommodating ACL graft 1 is hereby referred to as the tibial tunnel.
A successful ACL graft reconstruction depends on the proper positioning of the tibial tunnel through which the graft passes. If the tibial tunnel is not correctly positioned, the graft may impinge on the roof of the intercondylar notch of the femur when the knee fully extends, potentially rupturing the graft. In order to properly locate the position of the tibial tunnel to be drilled so that the ACL graft passing through it will not impinge on the roof, tibial guide devices such as the ones described in U.S. Pat. No. 5,300,077 and PCT publication WO94/00058 are often used. These devices use the roof of the intercondylar notch as a reference point to position the guidewire for drilling the initial hole.
The surgeon can also relieve impingement of an ACL graft on the roof of the intercondylar notch by performing a notchplasty procedure in which a portion of the bone forming the roof of the notch is removed. In general, the surgeon removes a portion of the bone of a size large enough to prevent impingement.